WhatsAppWeb: session restoration code

3 files changed, 68 insertions, 0 deletions

diff --git a/protocols/WhatsAppWeb/src/proto.h b/protocols/WhatsAppWeb/src/proto.h
index 06f8c7609f..7f8cff994a 100644
--- a/protocols/WhatsAppWeb/src/proto.h
+++ b/protocols/WhatsAppWeb/src/proto.h
@@ -40,6 +40,8 @@ class WhatsAppProto : public PROTO<WhatsAppProto>
 	CMStringA m_szJid, m_szClientId, m_szClientToken;
 	CMStringW m_tszAvatarFolder;
 
+	MBinBuffer mac_key, enc_key;
+
 	EVP_PKEY *m_pKeys; // private & public keys
 
 	bool ShowQrCode(const CMStringA &ref);
@@ -62,11 +64,15 @@ class WhatsAppProto : public PROTO<WhatsAppProto>
 	void StartSession(void);
 	void ShutdownSession(void);
 
+	void ProcessChallenge(const CMStringA &szChallenge);
+
 	/// Request handlers ///////////////////////////////////////////////////////////////////
 
+	void OnRestoreSession(const JSONNode &node);
 	void OnStartSession(const JSONNode &node);
 
 	void ProcessPacket(const JSONNode &node);
+	void ProcessCmd(const JSONNode &node);
 	void ProcessConn(const JSONNode &node);
 
 	/// Avatars ////////////////////////////////////////////////////////////////////////////
diff --git a/protocols/WhatsAppWeb/src/server.cpp b/protocols/WhatsAppWeb/src/server.cpp
index 3a682e00fa..be9fc55200 100644
--- a/protocols/WhatsAppWeb/src/server.cpp
+++ b/protocols/WhatsAppWeb/src/server.cpp
@@ -199,10 +199,57 @@ void WhatsAppProto::OnLoggedOut(void)
 	setAllContactStatuses(ID_STATUS_OFFLINE, false);
 }
 
+//////////////////////////////////////////////////////////////////////////////////////
+
+void WhatsAppProto::ProcessChallenge(const CMStringA &szChallenge)
+{
+	if (mac_key.isEmpty()) {
+		ShutdownSession();
+		return;
+	}
+
+	size_t cbLen;
+	void *pChallenge = mir_base64_decode(szChallenge, &cbLen);
+
+	BYTE digest[32];
+	unsigned cbResult = sizeof(digest);
+	HMAC(EVP_sha256(), mac_key.data(), mac_key.length(), (BYTE*)pChallenge, cbLen, digest, &cbResult);
+
+	ptrA szServer(getStringA(DBKEY_SERVER_TOKEN));
+	CMStringA payload(FORMAT, "[\"admin\",\"challenge\",\"%s\",\"%s\",\"%s\"]",
+		ptrA(mir_base64_encode(digest, cbResult)).get(), szServer.get(), m_szClientId.c_str());
+	WSSend(payload);
+}
+
+//////////////////////////////////////////////////////////////////////////////////////
+
 void WhatsAppProto::RestoreSession()
 {
+	ptrA szClient(getStringA(DBKEY_CLIENT_TOKEN)), szServer(getStringA(DBKEY_SERVER_TOKEN));
+	if (szClient == nullptr || szServer == nullptr) {
+		ShutdownSession();
+		return;
+	}
+
+	CMStringA payload(FORMAT, "[\"admin\",\"login\",\"%s\",\"%s\",\"%s\",\"takeover\"]", szClient.get(), szServer.get(), m_szClientId.c_str());
+	WSSend(payload, &WhatsAppProto::OnRestoreSession);
+}
+
+void WhatsAppProto::OnRestoreSession(const JSONNode &root)
+{
+	int status = root["status"].as_int();
+	if (status != 200) {
+		debugLogA("Attmept to restore session failed with error %d", status);
+		delSetting(DBKEY_CLIENT_TOKEN);
+		delSetting(DBKEY_SERVER_TOKEN);
+
+		ShutdownSession();
+		return;
+	}
 }
 
+//////////////////////////////////////////////////////////////////////////////////////
+
 void WhatsAppProto::ShutdownSession()
 {
 	if (m_bTerminated)
@@ -217,6 +264,8 @@ void WhatsAppProto::ShutdownSession()
 	OnLoggedOut();
 }
 
+//////////////////////////////////////////////////////////////////////////////////////
+
 void WhatsAppProto::StartSession()
 {
 	CMStringA payload(FORMAT, "[\"admin\",\"init\",[0,3,4940],[\"Windows\",\"Chrome\",\"10\"],\"%s\",true]", m_szClientId.c_str());
@@ -400,6 +449,18 @@ void WhatsAppProto::ProcessPacket(const JSONNode &root)
 
 	if (szType == "Conn")
 		ProcessConn(content);
+	else if (szType == "Cmd")
+		ProcessCmd(content);
+}
+
+void WhatsAppProto::ProcessCmd(const JSONNode &root)
+{
+	CMStringW wszType(root["type"].as_mstring());
+	if (wszType == L"challenge") {
+		CMStringA szChallenge(root["challenge"].as_mstring());
+		if (!szChallenge.IsEmpty())
+			ProcessChallenge(szChallenge);
+	}
 }
 
 void WhatsAppProto::ProcessConn(const JSONNode &root)
diff --git a/protocols/WhatsAppWeb/src/stdafx.h b/protocols/WhatsAppWeb/src/stdafx.h
index 171e384674..82f1e715c0 100644
--- a/protocols/WhatsAppWeb/src/stdafx.h
+++ b/protocols/WhatsAppWeb/src/stdafx.h
@@ -43,6 +43,7 @@ Copyright © 2019 George Hazan
 #include <m_gui.h>
 
 #include <openssl/evp.h>
+#include <openssl/hmac.h>
 
 #include "../../libs/libqrencode/src/qrencode.h"
 #include "../../libs/libsignal/src/curve.h"